Settling product in a package

ABSTRACT

System, hardware, and methods for agitating a package pre-form containing a charge of product elements thus to provide for product settling in the package pre-form before forming the final transverse seal. The product is caused to settle in the package pre-form by apply a plurality of rapid jerk-type acceleration forces to the packaging material, thus to cause rapid longitudinal and/or lateral acceleration in the packaging material.

BACKGROUND

Vertical Form Fill and Seal (VFFS) machines have been used for many years to package a wide variety of products in bags made with flexible packaging material.

In a VFFS machine, product is inserted into flexible packaging material as the packaging material is being formed into a flexible package, the product flowing along a downwardly-directed path, by the force of gravity into a package pre-form. The process involves:

-   -   drawing flexible packaging material, as a flat sheet, from a         generally continuous roll of such material,     -   advancing the packaging material through a forming collar and         about an outer surface of an upwardly-oriented forming tube and         thereby partially forming a package, including making a         longitudinal seal in the packaging material where         longitudinally-extending edges of the packaging material overlap         each other, and forming a transverse seal at the bottom of the         partially formed package, thereby making a package pre-form,     -   measuring a predetermined quantity of the product to be         packaged, and advancing the metered quantity of product to a         position overlying the package pre-form,     -   dropping the metered quantity of product down through the         forming tube and into the package pre-form, and     -   subsequently sealing the top of the package pre-form and cutting         the sealed package away from the trailing portion of the         packaging material after again advancing the packaging material.

One objective of the packager, who uses VFFS machines, is to meet regulatory requirements that the package state the quantity of product in the package. The quantity of product in the package is typically printed on the package, stating the weight of product contained in the package. Thus, it is critical to the packager that the weight of product in the package is always within the tolerances allowed by e.g. government regulation.

In meeting the weight requirements, the packager faces a variety of challenges. For example, the raw material used in manufacturing the e.g. food product may vary with time, or may vary when sourced from more than one supplier. For example, the process used in manufacturing the e.g. food product may vary with time, or may vary between different manufacturing facilities. For example, the packaging material may vary with time, or may vary when sourced from more than one supplier.

The challenge for the packager is to provide a quality package, where the weight of product in the package consistently meets regulatory requirements, where the packages use a consistent quantity/length of packaging material for each package unit, while consistently presenting the consumer with a package which appears to be “full” of the product.

If the package appears to be less than “full”, the consumer perceives that he/she has been cheated. If the package is overfull, the packager experiences a unacceptably high incidence of leakers which must be discarded as not meeting quality standards.

Another objective of the packager relates to the cost of the packaging material. It is not uncommon for the cost of the packaging material to represent a significant fraction of the overall cost of producing the packaged product. Accordingly, the packager has an incentive to limit the quantity of packaging material used in fabricating each unit of the packaged product.

Certain characteristics of the finished product can provide additional challenges to the packager. For example, the product may be fragile, and/or the product may be light weight, and/or the product may be non-uniform, product element to product element. Such product characteristics are taken into consideration when setting up the packaging operation.

Even where the product is not fragile, or not light weight, or not non-uniform, the product can still arrive in the package pre-form in a bulk density which is less than desired. Accordingly, increasing the bulk density of the product in the package, as well as improving the consistency of the density, package to package, is desirable for the packager.

The package forming action of a vertical form fill and seal operation starts by drawing a generally continuous length of flexible packaging material from one or more rolls of e.g. flexible film or flexible laminate and advancing the packaging material to typically the top of a rigid, typically metal, forming tube, wrapping the packaging material about the forming tube, and drawing the packaging material in a downward direction along an outer surface of an outside wall of the forming tube, thus to define side walls of the package/bag being produced.

In the process of so transforming the flat roll stock into a tubular construct, the flat roll stock is advanced over and about a forming shoulder which is located at the top of the forming tube. As the packaging material passes over and about the forming shoulder, the flat roll stock is converted to a tubular construct. The forming tube is so sized and configured that, as the packaging material is formed about the forming tube and into the tubular construct, the width of the continuous length packaging material is overlapped longitudinally onto itself. A longitudinal seal is subsequently formed by a heated elongate platen pressing the packaging material against the forming tube at the longitudinal overlap. In the alternative, the longitudinal seal can be formed as what is known as a fin seal.

A transverse seal bar forms a first transverse seal across the width of the tubular construct below the forming tube at about the same time, transforming the tubular structure into a longitudinally sealed, tubular construct, contiguous with a trailing portion of the roll stock, the tubular construct defining a package pre-form sealed closed at the lower end thereof and being open at the respective upper end of the tubular construct.

Simultaneously with the forming of the first transverse seal at the lower end of the tubular construct, the transverse seal heads also form a second transverse seal immediately adjacent the first transverse seal, at the top of the underlying, and next preceding, tubular construct, thus to close and seal that next preceding tubular construct as a closed and sealed package. The transverse seal apparatus can also make a transverse cut across the width of the tubular construct between the first and second transverse seals.

The transverse seal formed at the bottom of the formed tube of packaging material, in combination with the longitudinal seal along the length of the tube, provides a partially confined volume as a package pre-form, such that the so-partially-formed tube can receive and contain, and thereby capture and hold, and control the location of, the measured quantity of product which is subsequently dropped downwardly into the tube.

Once the package has been partially formed by the formation of the longitudinal seal, and by the formation of the first transverse seal at the bottom of the partially-formed package, a measured quantity of product is fed to a location over the top of the package, and is dropped downwardly under the force of gravity into the forming tube, and into the partially formed, longitudinally sealed tubular package construct. After the predetermined quantity of product has been dropped, the packaging material is again advanced, downwardly below the forming tube, as the next following length of packaging material is fed over the forming tube. The next following length of packaging material is sealed longitudinally at the platen and is sealed transversely below the forming tube. As the transverse seal jaws move against the packaging material to form the lower transverse seal in the next following length of packaging material, the seal jaws also form the top, and closing, seal in the underlying package and optionally cut the so closed and sealed underlying package away from the overlying next following length of packaging material.

The basic concept of the vertical form fill and seal design requires that flexible packaging material to be drawn/moved one package/unit each time a measured quantity of product is fed/dropped into the top of the forming tube.

Multiple different methods have been used to draw the film about the forming shoulder and down over the forming tube. Early machines had movable transversely-extending seal jaws generally mounted to a carriage which moved the jaws up and down, as well as moving the seal jaws transversely toward and away from the packaging material in forming the transverse seals.

Such movement of the transverse seal jaws was typically a sinusoidal motion whereby the transverse seal jaws moved upwardly to the top of the stroke, below the forming tube, as the jaws transitioned from a closed, sealing configuration, to a generally open configuration. At the top of the stroke, the sealing jaws would close on the next length of the flexible packaging material, above the product which had been dropped into the package pre-form, and thereby flatten the top of the tube while sealing the top of the underlying filled package and the bottom of the overlying next second length of packaging material which was still in the process of being formed into a package, and wherein the longitudinal seal had already been formed.

Heat would be applied to the closed seal jaws so as to seal the packaging material transversely on itself and to cut away the closed and sealed package/bag as the next second length of the packaging material was drawn over and onto the forming tube as the still-closed sealing jaws moved in a downward direction. During the downward pull, a knife, or a heated wire, located between the upper and lower sealing jaws severed the underlying filled package from the overlying tube which was still in the process of being formed.

When the sealing jaws had progressed down by a unit package length, the sealing jaws were opened to release the so-sealed and severed underlying package. This automatically stopped the film pull and stopped the transverse-seal-and-cut operation. At the same time, the product-filled first package, which had just been produced and cut away, dropped onto a discharge conveyor or the like, and the next/second overlying length of packaging material, already longitudinally sealed, was drawn to a position where the top of that length of material was below the forming tube.

The platen then made the longitudinal seal on the next/third length of packaging material, after which a next second measured quantity of product was dropped into the top of the forming tube thus into the partially-formed second package, while the now-open transverse seal jaws moved to the upper extremity of their range of movement where the pull cycle began again, with the transverse seal jaws closing on the top of the second length of packaging material, thus flattening the packaging material between the seal jaw surfaces at the top of the second package being formed, with the product trapped between the earlier-formed bottom seal of that second bag, and the now-being-formed top seal.

Speeds in the above-described method were limited by the inertias involved in moving the heavy transverse sealing structure up and down. An additional problem related to the requirement to provide electrical power to seal jaw heaters, and to provide cable connections to temperature sensors. Because of the constant flexing of the respective electrical connections when moving the seal jaws up and down, the electrical cables would periodically break, accompanied by corresponding maintenance and out-of-service costs.

In a subsequent version of VFFS devices, pull belt devices were located on each side of the rigid forming tube, alongside the platen, to pull the packaging material. These devices consisted of two belts, either driven by a single prime mover operating in cooperation with a gearbox, or driven by two individual prime movers, each driving one of the pull belts. Such devices would run for a programmed period of time to pull/draw a desired length of flexible packaging material onto the forming tube, and then stop while the platen engaged the packaging material in forming a longitudinal seal. The significant advantage with the pull belt system was that the transverse sealing hardware/jaws could be fixed vertically in position with respect to the machine frame, thus to move only horizontally. While the open/close motion still had to be accommodated by the electrical cables, this eliminated the up and down motion of the jaws of the previous generation of VFFS machines, with a respective reduction in cable failures.

Another version of the pull belt design had the pull belts continuously advancing while incorporating a drive for moving the pull belts into contact with the flexible packaging material to pull packaging/bag material down along the rigid forming tube, and for moving the pull belts away from the packaging material when it was not desired to pull packaging material down along the forming tube.

In a subsequent version of the pull belt design, a set of measure rollers was added upstream from the pull belts to better control the bag length. Bag length was initially entered in machine degrees in a software program or recipe which could be stored for future use. In some versions, bag length was entered into the control system in millimeters.

In some versions which used the measure rollers, a mechanical gearbox with a fixed gear ratio was used to drive the measure roller, which determined the bag length, whereby the gearbox controlled the operation of the system.

Pull parameters for a 1/3-1/3-1/3 exemplary prior art, single-pull profile, can be calculated as follows:

The velocity profile is assumed to be the 1/3-1/3-1/3 profile, but can be changed as required.

If a 250 mm bag is desired with 15 degrees of machine motion at 30 packages per minute, the programmed data are as follows:

Bag Length=250 mm

30 Packages/minute=2 seconds per machine cycle

15 Degrees=15/360 (2000 milliseconds)=83 ms

Command Counts=1000 Counts/Revolution

For this example, the calculation of velocity can be accomplished as follows:

-   -   a) The distance of 250 millimeters must be made in 83 ms.     -   b) The circumference of the measure roll is 6.38 inches or 162         mm     -   c) The 250 mm pull requires 1.543 revolutions.     -   d) 1.543 revolutions at 1,000 pulses per revolution require 1543         counts.     -   e) Thus, 1543 counts must be produced in 83 ms.     -   f) The velocity profile can be represented as illustrated in the         graph of FIG. 1 which shows velocity over the total pull time.

FIG. 1 represents the actual velocity profile which accelerates from 0 velocity to maximum velocity (VMAX) in 83/3 (27.67) ms, runs at VMAX for 83/3 (27.67) ms, and decelerates from VMAX to 0 in 83/3 (27.67) ms.

The profile of FIG. 1 can be regrouped into a rectangular waveform as illustrated in FIG. 2 with VMAX as the peak velocity, and 2/3 T or .6667×83 ms=55.3 ms. as the time.

Velocity Calculation

VMAX can be determined from the following equation:

Distance=(2×VMAX×T)/3

With Distance=250 mm=1.543 revolutions=1543 counts and T=83 ms

VMAX=(3×Distance)/(2×T)=4629 counts/166 ms=27.88 counts/ms=27,885 counts/sec

Acceleration and Deceleration Calculations

Acceleration=VMAX/(T/3)=27885×3/T=1,007,892 counts/sec/sec

Deceleration=−Acceleration=−1,007,892 counts/sec/sec

The above algorithms provide key elements of the pull, the maximum velocity, and the acceleration and deceleration factors. If no registration is required, a controller, using the calculated profile, will operate the system satisfactorily, dispensing the desired bag lengths. Changing any pull parameter (pull length, pull degrees, or machine speed) will cause the system to recalculate the parameters and adjust the respective drives accordingly.

The above calculation illustrates the computation for a single pull. Conventionally, a unit package is pulled in one or two pulls depending on the length of the longitudinal seal. If the package length is longer than the longitudinal platen seal bar, then two or more pulls are used for a given package unit. FIG. 3 illustrates the velocity profile for a two-pull package. Whatever the number of pulls, the longitudinal seal platen engages the overlapped edges of the packaging material to form a longitudinal seal each time the package material velocity reaches zero. In a typical two-unit pull, each pull approximates half of a unit package length. The longitudinal back seal is performed at the end of each pull such that the ends of the respective longitudinal seals overlap each other, the lengths of the overlapping seals depending on the lengths of the packages being formed.

In some applications of VFFS packaging, some of the product, when dropped down through the forming tube, ended up in the sealing area of the packaging material after completion of the film pull or pulls. Closing of the seal jaws when product is in the seal area results in product being trapped in the attempted seal thus producing what is referred to in the industry as a leaker. This allowed the product to spill out of the bag, or allowed air to enter what should have been a sealed, air-tight package, whereby the resulting package could not pass quality control inspection.

One proposed solution to this problem of product ending up in the seal area was to make the bag longer by using longer lengths of packaging material for each bag, in anticipation that all product would fall past the seal area. While lengthening the bag resulted in some reduction in the number of leakers, packaging material is typically a substantial factor in the cost of producing a unit of packaged goods, especially in the case of snack food products. As a result, there is a financial incentive/motivation to limit the cost of packaging material. Accordingly, lengthening the bag is not an acceptable long-term option.

Another proposed solution to the leaker problem is to not use a longer length of packaging material, but rather to employ a shaker/settler which, for example may be a plate which repeatedly contacts and thus agitates, the partially-formed package, for example agitating a plate against the bottom of the package pre-form, after the product is dropped into the package pre-form. Such agitation against the outside of the packaging material settles the product in the package before the top seal is formed. In some implementations, such shaking provides enough settling of the product in the packaging material, and enough agitation of the product elements that any product elements in the seal area fall away from the seal area, and thus enable successful sealing of the package, sometimes while using a relatively shorter length of the packaging material.

Some snack food products which are not particularly fragile, such as popcorn, or more agitation tolerant products such as powders, are well suited to use of a shaker plate to help settle the product in the package in order to limit the amount of packaging material being used or to effect release of product from the seal area. However, using a mechanical settler/shaker is a problem for more fragile products such as numerous varieties of chips, and flake products such as breakfast cereals, which can be broken by the use of a machine element mechanically agitating against the outside surface of the packaging material.

Where, in the prior art, a plate or other shaker impacts the outside surface of the packaging material in the partially formed package, shaking typically takes place after the pull of packaging material has been completed and the packaging material is not moving, in which case the shaking adds to the total machine cycle time, and thus results in a lower number of packages being produced per minute. In some implementations, shaking constitutes a machine element tapping the outside surface of the packaging material on a side of the package pre-form, in order to encourage settling of the product contained in the package pre-form, after the product is deposited into the package pre-form and during the subsequent downward pull of packaging material. Regardless of the shaking configuration, such shakers/settlers share some common drawbacks, as follows:

Most implementations involve shaking the filled bag after the pull is completed, which adds to the total machine cycle time resulting in a lower through-put of packages per minute.

No matter what mechanism is used to impact the outer surface of the packaging material, the mechanical shaker/settler requires a driver coupled to a mechanical system to impart the shaking activity, thus requiring additional energy to operate the system.

For all known shakers, the mechanical systems can be adjusted to modify the shaking action being imposed on to the packaging material and the product being run. Thus, every time the machine is set up to run a different product SKU, the machine must be adjusted for producing that SKU. Such set-up capability adds a significant increment in initial equipment cost to the machine operator, as well as increased set-up time for any given product run, and additional machine elements to be maintained and/or repaired.

The somewhat violent nature of the shaking activity results in not infrequent mechanical failures of the shaking system, which failures are associated with increased maintenance and repair costs, as well as downtime costs.

The somewhat violent nature of the shaking activity can cause breakage or deformation of product in the package.

It is therefore desirable to provide an improved packaging system and methods which provides for product settling while overcoming the above problems.

Accordingly, it is desirable to provide systems and methods which leave the seal area clear of product without increasing the length of packaging material used per package unit.

It is also desirable to provide systems and methods which cause product to settle in the package pre-form before the final transverse closure seal is formed.

It is further desirable to provide such systems and methods wherein the application of energy to cause settling of the product is sufficiently gentle that product in the bag is not unacceptably damaged.

It is still further desirable to provide such systems and methods wherein the intensity of the agitation of the packaging material can be adjusted according to the energy input tolerance of the product being packaged.

It is yet further desirable to provide such systems and methods wherein the finished package presents the consumer with an apparently full package while using a consistent length/quantity of packaging material and limiting the quantity of packaging material used.

These and other objectives are resolved, or at least attenuated, by the various embodiments illustrated herein for the invention.

SUMMARY

This invention provides vertical form fill and seal machines and systems which include a settling feature which avoids use of any external object impacting the outer surface of the packaging material, and which causes settling of the product contained in a package of product being formed before the final transverse seal is made to form the closed and sealed package. The provided settling feature is highly adjustable, whereby the intensity of the energy transferred to the packaging material can be adjusted according to how fragile, or not, is the product which is to be packaged. For a product, such as popcorn, which has a relatively lower sensitivity to the settling energy input, the input energy intensity can be set relatively higher whereby the length of time over which the settling energy input is needed, in order to achieve a particular degree of settling, may be relatively shorter. By contrast, for a product, such as potato chips, which have a relatively higher sensitivity to the intensity of the settling energy, the energy intensity input can be set relatively lower whereby the product is effectively caused to settle as desired, without the product being damaged by the settling process. However the length of time over which the settling energy input is needed in order to achieve a given degree of settling may be relatively longer for a lower energy intensity input than for a higher energy intensity input.

The settling feature is provided by using the VFFS machine controller to drive the drive system, for example to drive measure rollers, and respective pulling belts, at rapidly changing speeds, whereby the measure rollers and pulling belts advance the packaging material in a series of jerks, which can also be referred to as a stutter-step drive of the rollers and belts. The collective stutter step advance of the measure rollers and pulling belts causes the packaging material to advance at a corresponding stutter step motion and rate.

The stutter step advance of the packaging material causes motion both in the packaging material and within the product contained in the packaging material.

The overall result of the so-imposed motion is that the product elements in the package-being-formed are set into motion. Product elements which are loosely attached to the packaging material in the seal area are released from such attachment and tend to fall by gravity into the mass of the contained product, whereby the seal area is freed from at least some, typically all, of the product which would have otherwise stayed attached to the packaging material in the seal area. In addition, the collective motion of the packaging material and the contained product elements causes the product to settle in the package pre-form such that the height of the top of the product is lowered. Such lowering of the top of the product contents in the package pre-form enables the packager to limit the quantity of packaging material used to package the product.

In a first family of embodiments, the invention comprehends, in a package forming process wherein a supply of packaging material is fed onto and past a forming tube, the forming tube having a feed end and an exit end, longitudinal seals, each having a length, being formed at facing longitudinally-extending edge portions of the packaging material, thus to form a longitudinally sealed packaging tube, a transverse end closure being formed across the longitudinally sealed packaging tube at a portion thereof which has progressed past the exit end of the forming tube to thereby form a package pre-form extending from the transverse end closure to an opposing open end of the longitudinally sealed packaging tube, and wherein a charge of product elements is fed into the opposing open end of the longitudinally-sealed tube, a method of settling the product elements in the package pre-form, comprising advancing the package pre-form using at least first and second jerks, stopping the jerk advance, and after stopping the jerk advance, forming a subsequent longitudinal seal on a trailing portion of the packaging material, each jerk, before stopping the jerk advance, advancing the package pre-form a distance less than the length of the subsequent longitudinal seal.

In some embodiments, the method is implemented using a vertical form fill and seal packaging machine.

In some embodiments, the longitudinal seals are formed as one of fin seals or overlapping seals.

In some embodiments, the method includes advancing the package pre-form using at least first, second, and third jerks, and maintaining a sustained maximum velocity for a limited time for each of the jerks.

In some embodiments, the method includes advancing the package pre-form using at least first, second, third, fourth, and fifth jerks, and maintaining a sustained maximum velocity for a limited time for at least one of the jerks.

In some embodiments, the method includes advancing the package pre-form using at least first, second, and third jerks, and wherein time at maximum velocity for at least one of the jerks is essentially zero.

In some embodiments, the method includes advancing the package pre-form using at least first, second, and third jerks, each such jerk having an acceleration, a maximum velocity, and a minimum velocity, and wherein the minimum velocity following at least one of the jerk accelerations is substantially greater than zero.

In some embodiments, the minimum velocity is at least fifty percent as great as the maximum velocity.

In some embodiments, at least one of the jerks includes a sustained maximum velocity.

In some embodiments, at least first and second longitudinal seals, forming a continuation of the longitudinally sealed packaging tube, being formed for a given package pre-form, the advancing of the package pre-form, using at least first and second jerks, being implemented after the formation of at least one, but less than all, of the longitudinal seals made after the given package pre-form has been created.

In some embodiments, the advance using the jerks occurs during the first advance after product elements have been fed into the given package pre-form.

In a second family of embodiments, the invention comprehends a method of settling product elements in a package pre-form before final closure of the package pre-form to form a closed and sealed package, wherein a length of packaging material has been fed onto a feed end of a forming tube, formed into a longitudinally sealed packaging tube, and at least a lead end of the sealed packaging tube has been advanced past an exit end of the forming tube and has a transverse seal extending thereacross, the method comprising agitating the package pre-form, and thus agitating the product elements contained therein, without mechanical touching of any outside surface of that portion of the packaging material which extends past the exit end of the forming tube.

In some embodiments, the method includes agitating the package pre-form by advancing the package pre-form using at least first, second, and third jerks.

In some embodiments, the method includes applying a jerk force to the package pre-form in the advance direction while preventing the packaging pre-form from advancing.

In some embodiments, the longitudinally sealed packaging tube has been formed by making a plurality of longitudinal seals, at least first and second ones of the longitudinal seals having been formed for a given package pre-form, the agitating of the given package pre-form being implemented after the formation of at least one, but less than all, of the longitudinal seals made after the given package pre-form has been created.

In some embodiments, the advance using the jerks occurs during the first advance after product elements have been fed into the given package pre-form.

In a third family of embodiments, the invention comprehends a method of forming a package using a packaging machine having a forming tube, the forming tube having a feed end and an exit end, the method comprising intermittently advancing lengths of packaging material, connected to each other, onto a feed end of the forming tube, and forming longitudinal seals at facing edge portions of the packaging material and thereby forming the lengths of packaging material into respective lengths of a longitudinally sealed packaging tube, and along with the advancing of the lengths of packaging material onto the forming tube; forming the longitudinal seals, advancing the lengths of packaging material sequentially past the exit end of the forming tube and forming lead transverse closures across the longitudinally sealed packaging tube at a transverse seal location past the exit end of the forming tube, thus to make package pre-forms, each such package pre-form, when the respective lead transverse closure is formed, extending from the respective lead transverse closure to an opposing open end of the longitudinally sealed packaging tube; after the forming of a given such lead transverse closure, feeding a charge of product elements into the open end of the longitudinally sealed tube and thence into the package pre-form; with the charge of product elements in the given package pre-form, agitating the package pre-form, and thus the product elements contained therein, by advancing the package pre-form using at least first and second jerks; after advancing the package pre-form a distance sufficient to move a trailing portion of the charge of product elements to a location past the transverse seal location, stopping the jerk advance; and after stopping the jerk advance, forming a trailing longitudinal seal on a trailing portion of the package pre-form, thereby to convert the package pre-form into a closed and sealed package, and severing the closed and sealed package from the advancing lengths of packaging material, and forming the lead transverse closure on the next succeeding length of packaging material.

In some embodiments, the method is implemented using a vertical form fill and seal packaging machine.

In some embodiments, the method includes advancing the package pre-form using at least first, second, and third jerks, optionally first, second, third, fourth, and fifth jerks.

In some embodiments, the method includes advancing the package pre-form using at least first, second, and third jerks, and wherein time at maximum velocity for at least one of the jerks is essentially zero.

In some embodiments, the method includes each jerk having a jerk acceleration, a maximum velocity, and a minimum velocity, and wherein the minimum velocity following at least one of the jerk accelerations, in at least one of the jerks, is substantially greater than zero.

In a fourth family of embodiments, the invention comprehends a method of forming a package using a packaging machine having a forming tube, the forming tube having a feed end and an exit end, the method comprising advancing a first package unit length of a packaging material from a supply of such packaging material onto the forming tube at the feed end of the forming tube, and forming the first package unit length of packaging material into a tubular construct on the forming tube, with opposing first edge portions of the first package unit length facing each other; stopping the advance of the first package unit length of packaging material, and while stopped, forming a first longitudinal seal at the first facing edge portions, thus to form a circumferentially-closed, longitudinally sealed tube, the first longitudinal seal having a first length, a first leading end, and a first trailing end; advancing a second package unit length of the packaging material, which is connected to the first package unit length, from the supply of packaging material and onto the forming tube, and thereby advancing the first and second package unit lengths together, and thereby forming the second packaging unit length into a continuation of the tubular construct, with facing second edge portions of the second packaging unit length facing each other, and stopping the advance of the first and second packaging unit lengths, and while stopped, forming a second longitudinal seal at the second facing edge portions, the second longitudinal seal having a second length, a second leading end, and a second trailing end, the second longitudinal seal being a continuation of the first longitudinal seal, the advancing of the second package unit length being effective to also advance a portion of the longitudinally sealed tube beyond the exit end of the forming tube; forming a lead transverse end closure across the portion of the longitudinally sealed tube which has advanced beyond the exit end of the forming tube, thus to form a tubular package pre-form extending from the lead transverse end closure to an opening at the second trailing end of the second longitudinal seal; feeding a charge of product elements into the package pre-form at the opening at the second trailing end; and with the charge of product elements in the package pre-form, advancing a third package unit length of the packaging material, which is connected to the second package unit length, from the supply of packaging material and onto the forming tube, and thereby advancing the first, second, and third package unit lengths together, and forming the third package unit length into a continuation of the tubular construct, with facing third edge portions of the third package unit length facing each other, and stopping the advance of the first, second, and third package unit lengths, and while stopped, forming a third longitudinal seal at the third facing edge portions thereby to convert the package pre-form into a closed and sealed package, and simultaneously severing the closed and sealed package from the trailing second package unit length and forming a lead transverse closure at a leading edge of the second package unit length of the packaging material, the third longitudinal seal being a continuation of the second longitudinal seal, the advancing of the first, second, and third package unit lengths of the packaging material, after the forming of the second longitudinal seal, comprising advancing the packaging material using at least first and second jerks before stopping the advance and forming the third longitudinal seal, each such jerk advancing the package pre-form a distance less than the third length of the third longitudinal seal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph representing a typical single-pull prior art velocity profile.

FIG. 2 is a regrouped, rectangular waveform illustration of the velocity profile of FIG. 1.

FIG. 3 is a graph representing a typical double-pull prior art velocity profile.

FIG. 4 is a schematic side elevation view of a packaging system of the invention, showing a step where product has been dropped into a partially-formed package to form a pre-formed tube.

FIG. 5 is a schematic side elevation view as in FIG. 4 where the top seal is being formed in the product-filled package and the bottom seal is being formed in the next trailing length of packaging material.

FIG. 6 is a schematic side elevation view as in FIGS. 4 and 5 where the filled and sealed bag has dropped onto a take-away conveyor, and the system is ready to fill the next length of packaging material.

FIG. 7 is a schematic side elevation as in FIGS. 4-6 where the next charge of product has been dropped into the next trailing length of packaging material, and the pull belts are driving the next trailing length of packaging material downwardly using the stutter step method of the invention.

FIG. 7A shows a side elevation view of one of the pull belts of FIG. 7, engaging the packaging material against the forming tube and driving the packaging material downwardly using the stutter step method of the invention.

FIG. 8 is a flow chart illustrating an exemplary set of steps used in the invention.

FIG. 9 shows a velocity/time profile using a three-step pull where the sustained maximum-velocity time periods are longer than the acceleration and deceleration time periods.

FIG. 10 shows a velocity/time profile where both the sustained maximum velocity, and the number of stutter step pulls, are increased relative to those of FIG. 9.

FIG. 11 shows a velocity/time profile where the maximum velocity time period is essentially zero.

FIG. 12 shows a velocity/time profile where the velocity is reduced to something greater than zero during the intermediate reduced-velocity portions of the stutter steps and the frequency is modified.

FIG. 13 shows a velocity/time profile having multiple sustained maximum velocities portions, separated by reduced velocity portions where velocity is at all times greater than zero and the frequency is modified.

The invention is not limited in its application to the details of construction, or to the arrangement of the components or methods set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various other ways. Also, it is to be understood that the terminology and phraseology employed herein is for purpose of description and illustration and should not be regarded as limiting. Like reference numerals are used to indicate like components.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Turning now to FIG. 4, a packaging system 10 of the invention is controlled by a controller 12, typically a programmable logic computer. The primary activity of the system is implemented using a vertical form fill and seal (VFFS) machine 14 which is illustrated herein, but is not necessarily limited to only VFFS machines. A first guide roll 16 is positioned between a packaging material feed roll 18 and a pair of measure rolls 20 which form a nip 22 therebetween. A second guide roll 24 is located downstream of nip 22. A registration sensor 26 is positioned between second guide roll 24 and nip 22. Downstream of second guide roll 24 is forming shoulder 28 which is generally mounted above an elongate, downwardly-extending, forming tube 30 at the upwardly-disposed feed end 30A of the forming tube. An elongate seal-forming platen 32 is mounted in an upright orientation, intermittently pressing against forming tube 30. First and second pull belts 34 are mounted in upright orientations adjacent, and pressing against the forming tube, on opposing sides of platen 32 and driven so as to advance downwardly against the forming tube. First and second seal heads 36A, 36B are mounted below the downwardly-disposed exit end 30B of the forming tube, in opposition to each other, and are spaced closely outside a downward projection of the forming tube. Take-away conveyor 38 is located under forming tube 30 and under seal heads 36A, 36B. Feed roll 18 is mounted in a suitable location so as to provide a generally continuous length of rolled packaging material to VFFS machine 14. A product hopper 42 is positioned above and adjacent forming shoulder 28 so as to be able to drop product 44 into the underlying forming tube. Each seal head 36A, 36B includes an upper heat seal jaw 46, a lower heat seal jaw 48, and a cutting element 50 between the upper and lower seal jaws.

Packaging material 40 is selected, designed, and/or configured such that any two facing surfaces of the packaging material can be heat sealed to each other. Thus, overlapping opposing surfaces are sealed to each other to form longitudinal seals, and facing elements of a given surface are sealed to each other to form transverse seals.

FIG. 4 shows the system at the stage where packaging material has been drawn over first guide roll 16, through nip 22, past registration sensor 26, past second guide roll 24, over forming shoulder 28, and onto forming tube 30. Forming shoulder 28 and forming tube 30 have collectively formed the previously flat sheet of packaging material into a tubular orientation about forming tube 30, with longitudinal edge portions of the packaging material oriented generally vertically and facing each other, either as overlapping edge portions or as facing portions which can be formed into fin seals. Longitudinal seal platen 32 has formed a plurality of lengths of such longitudinal seals, with the lengths of the seals overlapping each other, whereby each such seal is a continuation of the next preceding longitudinal seal, thus to have formed a longitudinally-sealed tube. A bottom transverse seal 52 has been formed at the apparent leading edge of the longitudinally-sealed tube, thus to form a tubular package pre-form 53, sealed at the bottom, open at the top, and continuously longitudinally sealed from the transverse seal to a height corresponding to the top of platen 32. A first charge of product 44 has been fed/dropped from hopper 42 into the package pre-form. A second charge of product 44 is seen in FIG. 4 in the process of being fed/dropped into hopper 42 as indicated by arrows 45. The pre-form has been advanced downwardly, using a jerky stutter step-type drive motion of the invention, described in more detail following. Seal heads 36A, 36B are withdrawn away from, but are adjacent, the sides of the package pre-form. Top 54 of product 44 in the package pre-form is below the bottoms 56 of the seal jaws, and below the bottom of transverse seal area 58, the transverse seal area being illustrated by stippling in FIG. 4 between the seal jaws. The seal area is desirably, and typically, would be free from, namely devoid of, product 44.

FIG. 5 shows the packaging system of FIG. 4 with heat seal heads 36A, 36B closed on the tubular package pre-form at the seal area. In FIG. 5, the lower heat seal jaws 48 are forming a top transverse heat seal 60 across the top of the underlying length of the package pre-form and above top 54 of the contained product, thus to finish closing and sealing the package pre-form with the product contained therein to make a closed and sealed package, containing the charge of product 44. Simultaneously, cutting element 50 engages the packaging material across the width of the package pre-form above top transverse heat seal 60, thus cutting away the underlying now-fully-sealed package 62 from the overlying package pre-form 53. As also shown in FIG. 5, simultaneously with the lower heat seal jaws forming the top heat seal on the underlying length of the package pre-form, upper heat seal jaws 46 are forming a bottom transverse heat seal 52 across the bottom of the next adjacent, and overlying, package unit length of packaging material, thus forming the next succeeding package pre-form.

FIG. 6 shows the packaging system of FIGS. 4 and 5 with the seal heads again withdrawn. As the seal heads withdrew from their sealing positions shown in FIG. 5, package 62 was released from the grip of lower seal jaws 48. Having been cut away from the package pre-form by cutting element 50, package 62 fell by gravity onto take-away conveyor 38. Thus, package 62 is shown on take-away conveyor 38 in FIG. 6. Also shown in FIG. 6, overlying hopper 42 has been fully recharged with the next charge of product 44, ready to be dropped into the package pre-form, and platen 32 has been advanced horizontally against the edges of the next length of packaging material, to form a continuation of the longitudinal seal in the longitudinally sealed tube.

FIG. 7 shows the next stage of the process, where the platen has been withdrawn from the packaging material at the forming tube as suggested by arrows 55, and the next charge of product has been dropped from hopper 42 into the underlying package pre-form.

A typical product which is dropped from hopper 42 is a dry food product. Examples of such dry food products are various snack products such as chip products. Potato chips, corn chips, tortilla chips, pita chips and the like are representative of such snack products. Another common product is dry breakfast cereals and other grain-related products. Still another product is popped popcorn. Such products have a number of product characteristics which make them susceptible to initially arriving in the bottom of the package pre-form in a relatively less dense condition, and which presents problems for the packager. Common characteristics include, without limitation:

-   -   The product is light weight.     -   The product is relatively fragile, easily broken.     -   The product is relatively dry.     -   The product has coefficient of friction which impedes, but does         not stop, movement of the product elements relative to each         other.     -   Product configuration, from product element to product element,         is non-uniform such that the product exhibits different shapes.         For example, potato chips all have approximately the same         thickness, but different individual chips in a given package         have different lengths and widths, and the chips tend to         bend/curl during cooking, and the bend/curl configurations         differ from chip to chip. For example, many breakfast cereals         contain multiple different ingredients, each having a different         three-dimensional shape/configuration. For example, raisin bran         contains both flakes and dried raisins.

Even where the product is not fragile, not light weight, not non-uniform, the product can still arrive in the package pre-form in a bulk density which is less than desired. Accordingly, increasing the bulk density of the product in the package, as well as improving the consistency of the density, package to package, is desirable for the packager.

As the product drops from hopper 42 into the package pre-form, the respective product elements lodge with respect to each other and with respect to the side walls of the package pre-form in keeping with their respective physical properties. Especially the light weight, varying configurations, and the friction properties affect the way the product elements come to rest relative to each other when first dropped into the package pre-form.

Still referring to FIG. 7, in the invention, once the charge of product has arrived in the package pre-form, controller 12 issues commands to measure rolls 20 and pull belts 34 such that the measure rolls and pull belts begin simultaneously advancing the packaging material. In the invention, such advance is a series of jerky downward stutter step movements of the package pre-form between respective advances and retractions of the platen in making longitudinal heat seals. The packaging material advance is a plurality of jerks, also referred to herein as stutter steps, between platen engagements when each advance represents a unit package.

The jerky stutter step advance is indicated in FIG. 7 by a first series of aligned and short, upwardly-directed arrows 62 spaced from each other on the outwardly-disposed portion of pull belt 34, and a second series of aligned and downwardly-directed arrows 64 spaced from each other under transverse bottom seal 52 on the package pre-form. FIG. 7A shows pull belt 34 in side elevation view, such that arrows 62 indicate an upward direction of advance on the outwardly-disposed portion of pull belt 34 as in FIG. 7, and a downward direction of advance on the inwardly-disposed portion of the belt which presses the packaging material against the forming tube.

Because the invention operates with a series of jerks, and intermediate periods of lesser velocity, or no velocity, the acceleration required to maintain desired throughput rates may, as a result, exceed the limitations/capabilities of the system, in which case adjustments may need to be made to one or more of the system parameters. For example, the total time required to complete a pull may have to be increased.

Assuming, for example, a 250 mm pull in 83 ms in 5 individual pulls, using the equations shown above, the calculation is as follows:

Velocity Calculation

Pull Length per segment=250/5=50 mm.

Pull time per segment=83/5=16.67 ms.

VMAX can then be determined as follows:

Distance=(2×VMAX×T)/3.

With Distance=50 mm=.3086 revolutions=308 counts and T=16.67 ms.

VMAX=(3×Distance)/(2×T)=924 counts/33.34 ms=27.71 counts/ms=27,710 counts/sec.

Acceleration and Deceleration Calculations

Acceleration=VMAX/(T/3)=27710×3/16.67=4,986,803 counts/sec/sec.

Deceleration=−Acceleration=−4,986,803 counts/sec/sec.

The above calculations show that the acceleration and deceleration requirements can become excessive and impose restrictions on the amount of film which can be pulled in the desired amount of time within the response limits of the system.

Certain steps can be taken to resolve the situation, for example and without limitation:

-   -   1) Decrease the packaging material pull length per package unit         length, and/or     -   2) Increase the packaging material pull time per package unit         length in the machine cycle, and/or     -   3) Decrease the number of programmed jerk moves per package unit         length in the packaging material pull cycle and/or     -   4) Decelerate to a speed greater than zero, and/or     -   5) Increase the energy input into the system, and/or     -   6) Replace the power supply and other appropriate machine         elements with elements having greater energy input rate         capacities.

One example of a flow chart which would accomplish the desired results is shown as FIG. 8. Other methods can be used depending on the capabilities afforded in the hardware being used to control the system.

As the measure rolls and pull belts engage the packaging material and affect the stutter step/jerk motion of advancing the packaging material, a number of motion elements can occur at the advancing package pre-form.

A first motion element is the primary motion of the packaging material, which creates a first motion differential between the packaging material and the contact product elements which are in contact with the packaging material.

A second motion element is the motion which is thus imparted to those contact product elements whereby those contact product elements, themselves, move.

A third motion element is a second motion differential which is created between the contact product elements and those non-contact product elements which are not in contact with the packaging material and which are in contact with the contact product elements.

A fourth motion element is the motion of those so contacted non-contact product elements, which is imparted by the contact product elements.

A fifth motion element is the motion imparted to all the remaining non-contact product elements as those product elements come into contact with a product element which is already in motion.

Example System

A Hayssen ® Ultima® VFFS machine is equipped with an Omron™ programmable logic computer as the control system, uniquely programmed to operate according to the invention.

The exemplary control system employs stepper motor technology to drive the measure rolls and pull belts. The configuration is illustrated in FIGS. 4-7 and 7A. The control system includes a motion control system for control of the stepper motors. The measure rolls are assigned as the master axis and the pull belts are set up in a follower mode to run at speeds which match the surface speeds of the measure rolls, thereby accommodating the mechanical ratio between the measure rolls and the pull belts. This ratio can be adjusted by the operator as needed to compensate for e.g. packaging material slip due to humidity, temperature, film characteristics, and other factors.

The pull belts follow the commanded position of the measure roll axis in an open loop configuration using stepper motors.

In the alternative, servo motors can be used e.g. in a closed loop configuration. In the closed loop configuration, the following function reflects the actual position of the master encoder rather than the open loop commanded position.

Another approach is to attach an encoder to the master axis and allow the pull belt axis to follow the encoder rather than the commanded position of the master axis. This forms a closed loop system which is very much like the closed loop servo system.

Conventionally, a unit package is pulled in one or two, optionally three or more, pulls depending on the length of the longitudinal back seal. If the package length is longer than the platen seal bar, the pull typically consists of two pulls, each of which approximates half of a unit package length. The longitudinal back seal is performed at the end of each pull when the packaging material is not moving, such that the ends of the respective longitudinal seals overlap each other, the lengths of the overlapping seals depending on the lengths of the packages being formed.

If the package length is equal to, or greater than, the length of the longitudinal platen seal bar, the invention comprehends the use of two pulls, or more, with a stutter step motion coincident with at least one of the pulls, to help the settling of product in the package pre-form. Restated, any time the package material is driven, with product in the package pre-form, the stutter step/jerk type drive is used unless multiple pulls are used for a given package unit.

Thus, an answer to the settling problem is found by breaking the continuous normal pull into a series of pulls or jerks between engagements of the longitudinal platen against the packaging material to form the longitudinal seals.

For example, if it is desired to pull a 20 inch bag, rather than making a single 20 inch pull, the invention makes a series of pulls, for example 20 one-inch pulls, or ten two-inch pulls, or five four-inch pulls, or six 3.33-inch pulls, each pull coming to a complete stop, or at least reducing pull speed, before starting the next pull. Since the machine controller, e.g. a programmable logic computer, is capable of dividing the pull by any number, using a variety of maximum velocities, a variety of minimum velocities, a variety of acceleration rates, a variety of deceleration rates, the film pull can be divided into any number of segments, recognizing that the greater the number of pulls, potentially the greater the total pull time, which may impact the total cycle time for forming, filling, and sealing the package.

The velocity of a given one of the pulls of the packaging material in forming a given package in the prior art is, for example and without limitation, commonly represented as a 1/3-1/3-1/3 profile. The first third of the pull starts at zero velocity and accelerates to the maximum velocity (VMAX). The second third of the pull is accomplished at the maximum calculated velocity for that pull, and the third and final portion of the pull decelerates the packaging material pull from the maximum velocity to zero velocity. This is the motion standard for the velocity calculations required to produce a package of a desired length in the prior art. The same time and velocity principles apply in the invention.

As illustrated in prior art FIGS. 1-3, for any given packaging material advance, the area under the time/velocity graph represents the linear distance of advance of the packaging material. Thus, for a given specified distance of advance, whatever the profile of the graph, the area under the graph must be the same. So for a stutter step advance rather than a single pull as in FIG. 1, either maximum velocity can be increased, or time can be increased, or acceleration and/or deceleration rates can be increased; or any combination of such elements can be used. Or the minimum velocity may be some value greater than zero for some or all of the stutter steps excluding, of course, the final step. A full stop must be achieved at least once for each unit package in order for the platen and seal heads to be able to form the longitudinal and transverse seals.

The velocity/time profile for such an advance of the packaging material using a three step, jerky/stutter step, pull is illustrated in FIG. 9, where the sustained maximum-velocity time periods are longer than the acceleration and deceleration time periods.

FIG. 10 shows a velocity/time profile similar to that of FIG. 9 where the sustained maximum velocity is increased relative to that of FIG. 9 over the same time period and the number of steps has been increased, as well as, using increased rates of acceleration and deceleration.

FIG. 11 shows a velocity/time profile where the maximum velocity time period is essentially zero.

FIG. 12 shows a velocity/time profile where the minimum velocity is greater than zero during the intermediate stutter steps/jerks and the frequency is modified relative to FIGS. 9-11.

FIG. 13 shows a velocity profile having multiple sustained maximum velocity portions, separated by reduced velocity portions where the velocity is at all times greater than zero and the frequency is modified relative to FIGS. 9-11.

In general, the profiles of FIGS. 9-13 show that a given length of packaging material can be advanced while using a wide variety of stutter step profiles. The variety of the available profiles which can be used with the stutter step method is limited only by the mechanical limits of the machine drives and the imagination of the user in setting up the instruction set in the software program which is entered into controller 12. Such wide variety of profiles allows the user to adapt the stutter step profile, and thus the stutter step pulls, to the particular product being packaged while ensuring a balance of

release of product from the seal area,

optimized product settling in the package,

use of limited package material length,

consistency of package results, and

acceptable quality control.

The calculations herein provide the key elements of the pull, the maximum velocity of each pull, and the minimum velocity of each jerk/stutter step as well as acceleration and deceleration factors for each pull. If no registration is required by printing on the packaging material, such calculated profile will operate the system, dispensing the desired package unit length each cycle. Where registration is required, registration sensor 26 senses a registration mark on the packaging material and alerts controller 12, which adjusts the drives to the measure rollers and/or the pull belts, thus to adjust the position of the registration mark relative to the cut-off of the finished, closed and sealed package.

Where more than one pull of packaging material, and more than one platen engagement are used for a given package unit, at least one, but not necessarily all, of the platen engagements, to form a longitudinal seal comes after a stutter step advance. Namely, some of the pulls/advances can be non-stutter step pulls/advances where multiple platen engagements are used for a given package unit. Accordingly, the stutter step jerky advance is used after the charge of product has been fed into the package pre-form, and may not be used during an advance where no product has yet been fed into the package pre-form.

Thus, for example, for a two-step advance of the packaging material, where the packaging material is advanced two times and two longitudinal seals are made, for a given package unit, the first advance may take place immediately after a charge of product elements has been fed into the package pre-form. Given that the product is in the package pre-form, and an objective of the jerky stutter step advance is to settle the product and/or remove product from the seal area, that first advance may follow a stutter step profile while the second advance may follow a profile more like that of FIG. 1. In the alternative, the first advance may be a conventional advance as in FIG. 1 and the second advance may be a jerky stutter step advance. So long as at least one of the advances is a stutter step advance, the objectives of product settling and/or product being freed from the seal area can be met.

In any event, the settling provided by the invention can be achieved without any mechanical device touching any outside surface of that portion of the packaging material which extends past the exit end of the forming tube, and without any physical touching of the packaging material by a human operator.

In a further embodiment, not illustrated specifically in the drawings, the advance of the packaging material can start as a conventional acceleration to maximum velocity as in FIG. 1, progress at constant VMAX velocity for a portion of the VMAX time shown in FIG. 1, and proceed as a jerky stutter step portion of the VMAX time, subsequently decelerating to zero velocity as in FIG. 1. Such embodiment thus envisions a velocity profile as in FIG. 1, modified by a jerky stutter step velocity profile as shown in for example any of FIGS. 9-13, for a portion, but less than all, of the time shown as VMAX in FIG. 1. Such modification can occur at any point along the time axis of FIG. 1, though typically, the jerky stutter step modification starts after velocity has reached VMAX.

Changing any pull parameter, such as pull length, pull degrees, machine speed, acceleration rate, deceleration rate, minimum velocity, maximum velocity, time at maximum velocity, time at minimum velocity, or print registration, will cause the system to recalculate the remaining pull parameters.

As used herein, a “jerk” advance of the packaging material means either both rapidly accelerating the packaging material and then decelerating the packaging material, or rapidly accelerating the packaging material, rapidly slowing the acceleration, and then again rapidly accelerating the packaging material.

In the alternative, a jerk can be a strong force rapidly applied to the packaging material in the direction of advance of the packaging material so as to rapidly apply acceleration tension to the film, such as a force calculated to reach a VMAX packaging material acceleration in ⅓ the anticipated pull time, but wherein the packaging material is prevented from advancing by a brake system. Such jerk force causes sufficient e.g. lateral flexing of the packaging material in the package pre-form to cause displacement of any product from the seal area and to at least initiate product element settling in the package pre-form.

At least first and second jerks are employed either before or after, or both before and after, the formation of a given one of the longitudinal seals. Thus, where a jerk-type advance of packaging material is used, at least two jerks are used to advance or otherwise tension the packaging material after formation of a given longitudinal seal and before formation of the next longitudinal seal.

Although the invention has been described with respect to various embodiments, this invention is also capable of a wide variety of further and other embodiments within the spirit and scope of the appended claims.

Those skilled in the art will now see that certain modifications can be made to the apparatus and methods herein disclosed with respect to the illustrated embodiments, without departing from the spirit of the instant invention. And while the invention has been described above with respect to the preferred embodiments, it will be understood that, in light of the disclosure here, the invention can be adapted to numerous rearrangements, modifications, and alterations, and all such arrangements, modifications, and alterations are intended to be within the scope of the appended claims.

To the extent the following claims use means plus function language, it is not meant to include there, or in the instant specification, anything not structurally equivalent to what is shown in the embodiments disclosed in the specification. 

Having thus described the invention, what is claimed is:
 1. In a package forming process wherein a supply of packaging material is fed onto and past a forming tube, the forming tube having a feed end and an exit end, longitudinal seals, each having a length, being formed at facing longitudinally-extending edge portions of the packaging material, thus to form a longitudinally sealed packaging tube, a transverse end closure being formed across the longitudinally sealed packaging tube at a portion thereof which has progressed past the exit end of the forming tube to thereby form a package pre-form extending from the transverse end closure to an opposing open end of the longitudinally sealed packaging tube, and wherein a charge of product elements is fed into the opposing open end of the longitudinally-sealed tube, a method of settling the product elements in the package pre-form, comprising: (a) advancing the package pre-form using at least first and second jerks, (b) stopping the jerk advance, and (c) after stopping the jerk advance, forming a subsequent longitudinal seal on a trailing portion of the packaging material, each jerk, before stopping the jerk advance, advancing the package pre-form a distance less than the length of the subsequent longitudinal seal.
 2. A method as in claim 1, implemented using a vertical form fill and seal packaging machine.
 3. A method as in claim 1 wherein the longitudinal seals are formed as one of fin seals or overlapping seals.
 4. A method as in claim 1, including advancing the package pre-form using at least first, second, and third jerks, and maintaining a sustained maximum velocity for a limited time for each of the jerks.
 5. A method as in claim 1, including advancing the package pre-form using at least first, second, third, fourth, and fifth jerks, and maintaining a sustained maximum velocity for a limited time for at least one of the jerks.
 6. A method as in claim 1, including advancing the package pre-form using at least first, second, and third jerks, and wherein time at maximum velocity for at least one of the jerks is essentially zero.
 7. A method as in claim 1, including advancing the package pre-form using at least first, second, and third jerks, each such jerk having an acceleration, a maximum velocity, and a minimum velocity, and wherein the minimum velocity following at least one of the jerk accelerations is substantially greater than zero.
 8. A method as in claim 7 wherein the minimum velocity is at least fifty percent as great as the maximum velocity.
 9. A method as in claim 7, at least one of the jerks having a sustained maximum velocity.
 10. A method as in claim 1, at least first and second longitudinal seals, forming a continuation of the longitudinally sealed packaging tube, being formed for a given package pre-form, the advancing of the package pre-form, using at least first and second jerks, being implemented after the formation of at least one, but less than all, of the longitudinal seals made after the given package pre-form has been created.
 11. A method as in claim 10 wherein the advance using the jerks occurs during the first advance after product elements have been fed into the given package pre-form.
 12. A method of settling product elements in a package pre-form before final closure of the package pre-form to form a closed and sealed package, wherein a length of packaging material has been fed onto a feed end of a forming tube, formed into a longitudinally sealed packaging tube, and at least a lead end of the sealed packaging tube has been advanced past an exit end of the forming tube and has a transverse seal extending thereacross, the method comprising agitating the package pre-form, and thus agitating the product elements contained therein, without mechanical touching of any outside surface of that portion of the packaging material which extends past the exit end of the forming tube.
 13. A method as in claim 12, implemented using a vertical form fill and seal packaging machine.
 14. A method as in claim 12, including agitating the package pre-form by advancing the package pre-form using at least first, second, and third jerks.
 15. A method as in claim 12 including applying a jerk force to the package pre-form in the advance direction while preventing the packaging pre-form from advancing.
 16. A method as in claim 12 wherein the longitudinally sealed packaging tube has been formed by making a plurality of longitudinal seals, at least first and second ones of the longitudinal seals having been formed for a given package pre-form, the agitating of the given package pre-form being implemented after the formation of at least one, but less than all, of the longitudinal seals made after the given package pre-form has been created.
 17. A method as in claim 16 wherein the advance using the jerks occurs during the first advance after product elements have been fed into the given package pre-form.
 18. A method of forming a package using a packaging machine having a forming tube, the forming tube having a feed end and an exit end, the method comprising: (a) intermittently advancing lengths of packaging material, connected to each other, onto a feed end of the forming tube, and forming longitudinal seals at facing edge portions of the packaging material and thereby forming the lengths of packaging material into respective lengths of a longitudinally sealed packaging tube; (b) along with the advancing of the lengths of packaging material onto the forming tube and forming the longitudinal seals, advancing the lengths of packaging material sequentially past the exit end of the forming tube and forming lead transverse closures across the longitudinally sealed packaging tube at a transverse seal location past the exit end of the forming tube, thus to make package pre-forms, each such package pre-form, when the respective lead transverse closure is formed, extending from the respective lead transverse closure to an opposing open end of the longitudinally sealed packaging tube; (c) after the forming of a given such lead transverse closure, feeding a charge of product elements into the open end of the longitudinally sealed tube and thence into the package pre-form; (d) with such charge of product elements in the given package pre-form, agitating the package pre-form, and thus the product elements contained therein, by advancing the package pre-form using at least first and second jerks; (e) after advancing the package pre-form a distance sufficient to move a trailing portion of the charge of product elements to a location past the transverse seal location, stopping the jerk advance; and (f) after stopping the jerk advance, forming a trailing longitudinal seal on a trailing portion of the package pre-form, thereby to convert the package pre-form into a closed and sealed package, and severing the closed and sealed package from the advancing lengths of packaging material, and forming the lead transverse closure on the next succeeding length of packaging material.
 19. A method as in claim 18, implemented using a vertical form fill and seal packaging machine.
 20. A method as in claim 18, including advancing the package pre-form using at least first, second, and third jerks.
 21. A method as in claim 18, including advancing the package pre-form using at least first, second, third, fourth, and fifth jerks.
 22. A method as in claim 18, including advancing the package pre-form using at least first, second, and third jerks, and wherein time at maximum velocity for at least one of the jerks is essentially zero.
 23. A method as in claim 18, each jerk having a jerk acceleration, a maximum velocity, and a minimum velocity, and wherein the minimum velocity following at least one of the jerk accelerations, in at least one of the jerks, is substantially greater than zero.
 24. A method of forming a package using a packaging machine having a forming tube, the forming tube having a feed end and an exit end, the method comprising: (a) advancing a first package unit length of a packaging material from a supply of such packaging material onto the forming tube at the feed end of the forming tube, and forming the first package unit length of packaging material into a tubular construct on the forming tube, with opposing first edge portions of the first package unit length facing each other; (b) stopping the advance of the first package unit length of packaging material, and while stopped, forming a first longitudinal seal at the first facing edge portions, thus to form a circumferentially-closed, longitudinally sealed tube, the first longitudinal seal having a first length, a first leading end, and a first trailing end; (c) advancing a second package unit length of the packaging material, which is connected to the first package unit length, from the supply of packaging material and onto the forming tube, and thereby advancing the first and second package unit lengths together, and thereby forming the second packaging unit length into a continuation of the tubular construct, with facing second edge portions of the second packaging unit length facing each other, and stopping the advance of the first and second packaging unit lengths, and while stopped, forming a second longitudinal seal at the second facing edge portions, the second longitudinal seal having a second length, a second leading end, and a second trailing end, the second longitudinal seal being a continuation of the first longitudinal seal, the advancing of the second package unit length being effective to also advance a portion of the longitudinally sealed tube beyond the exit end of the forming tube; (d) forming a lead transverse end closure across the portion of the longitudinally sealed tube which has advanced beyond the exit end of the forming tube, thus to form a tubular package pre-form extending from the lead transverse end closure to an opening at the second trailing end of the second longitudinal seal; (e) feeding a charge of product elements into the package pre-form at the opening at the second trailing end; and (f) with the charge of product elements in the package pre-form, advancing a third package unit length of the packaging material, which is connected to the second package unit length, from the supply of packaging material and onto the forming tube, and thereby advancing the first, second, and third package unit lengths together, and forming the third package unit length into a continuation of the tubular construct, with facing third edge portions of the third package unit length facing each other, and stopping the advance of the first, second, and third package unit lengths, and while stopped, forming a third longitudinal seal at the third facing edge portions thereby to convert the package pre-form into a closed and sealed package, and simultaneously severing the closed and sealed package from the trailing second package unit length and forming a lead transverse closure at a leading edge of the second package unit length of the packaging material, the third longitudinal seal being a continuation of the second longitudinal seal, the advancing of the first, second, and third package unit lengths of the packaging material, after the forming of the second longitudinal seal, comprising advancing the packaging material using at least first and second jerks before stopping the advance and forming the third longitudinal seal, each such jerk advancing the package pre-form a distance less than the third length of the third longitudinal seal.
 25. A method as in claim 24, implemented using a vertical form fill and seal packaging machine.
 26. A method as in claim 24, including advancing the package pre-form using at least first, second, and third jerks.
 27. A method as in claim 24, including advancing the package pre-form using at least first, second, third, fourth, and fifth jerks.
 28. A method as in claim 24, including advancing the package pre-form using at least first, second, and third jerks, and wherein time at maximum velocity for at least one of the jerks is essentially zero.
 29. A method as in claim 24, each jerk having a jerk acceleration, a maximum velocity, and a minimum velocity, and wherein the minimum velocity following at least one of the jerk accelerations, in at least one of the jerks, is substantially greater than zero. 